The Maori Council's final bid to delay the Government's flagship asset sales policy until Maori water claims are dealt with opens in the Supreme Court this morning with the Government saying it is confident it will win.

But a second Supreme Court case in two weeks time in which Waikato hapu Pouakani will seek to assert its ownership of a section of the Waikato River may prove to be yet another headache for the Government which hopes to sell shares in Mighty River Power soon.

High profile Queen's Counsel Colin Carruthers is leading the Maori Council's appeal of last year's High Court decision which found against the council's bid to delay the sale of shares in Mighty River Power until Maori water rights were dealt with by the Crown.

Maori Council lawyer Felix Geiringer said the council's arguments during the two day hearing beginning this morning would largely be the same as those made during the December High Court hearing. The council believed the sale of power company shares would affect the Crown's ability to make adequate compensation for Maori water claims which were not just about money.

The Government has consistently said the sale will have no impact on any future redress and State Owned Enterprises Minister Tony Ryall yesterday said the Government was confident of its position.

A favourable decision from the Supreme Court, would allow the Government to sell up to 49 per cent of Mighty River Power shares in the first half the year in the first part of its "mixed ownership model" by which hopes to raise $5 billion to $7 billion via asset sales to fund new infrastructure investments.

However Poakani, one of the Maori groups backing the council's legal challenge today, has a separate Supreme Court hearing later in February which may affect Mighty River.

Pouakani lawyer Miharo Armstrong said the case was a claim of ownership over a section of the Waikato riverbed near Mangakino where Mighty River had three dams.

Pouakani's successful challenge of the Crown's ownership of the riverbed in the Supreme Court last year paved the way for its case this month.

Mr Armstrong said the power company was sufficiently concerned by the action that it had sought and been granted joined in the proceeding.

Mr Armstrong said Mighty River was not a party to the case but were saying they would be affected by any relief or redress the court may order.

"They want to be heard on the issue of relief should it be granted and what form that should take... they believe it will affect them."

Pouakani chairman Tamati Cairns believed a favourable decision from the Supreme Court later this month would affect the Government's Mighty River sale plan.

"What do you do when you've got three dams sitting on land that doesn't belong to you and you're trying to sell shares in them? That's just not right."

Mr Ryall said the Government was unconcerned by the Pouakani hearing as it was separate case to the Maori Council's action.